*,
*:before,
*:after {
    box-sizing: border-box;
    margin    : 0;
    padding   : 0;
}

.container {
    display    : flex;
    flex-flow  : row nowrap;
    width      : 100vw;
    height     : 100vh;
    align-items: stretch;

    .ctrl {
        border-right: 1px solid #eee;
        flex        : 40vw 1 1;
    }

    .prev {
        flex: 60vw 1 1;
    }
}